package com.lxz.nio.demo;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class TimeClient {
	public static void main(String[] args){
		int port = 1234;
		if(args != null && args.length > 0){
			try{
				port = Integer.valueOf(args[0]);
			}catch(NumberFormatException e){
				//采用默认值
			}
		}
		new Thread(new TimeClientHandle("127.0.0.1", 1234), "TimeClient-001").start();
	}
}

class TimeClientHandle implements Runnable{
	private String host;
	private int port;
	private Selector selector;
	private SocketChannel socketChannel;
	private volatile boolean stop;
	
	public TimeClientHandle(String host, int port){
		this.port = port;
		this.host = host == null ? "127.0.0.1" : host;
		try{
			selector = Selector.open();//创建Reactor线程
			socketChannel = SocketChannel.open();//打开SocketChannel，绑定客户端本地地址（可选，默认系统会随机分配一个可用的本地地址）
			socketChannel.configureBlocking(false);//设置为非阻塞模式
		}catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
	}
	
	public void run() {
		try{
			doConnect();
		}catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
		while(!stop){//在无限循环体内轮询准备就绪的Key
			try{
				selector.select(1000);
				Set<SelectionKey> selectedKeys = selector.selectedKeys();
				Iterator<SelectionKey> it = selectedKeys.iterator();
				SelectionKey key = null;
				while(it.hasNext()){
					key = it.next();
					it.remove();
					try{
						handleInput(key);
					}catch(Exception e){
						if(key != null){
							key.cancel();
							if(key.channel() != null){
								key.channel().close();
							}
						}
					}
				}
			}catch(Exception e){
				e.printStackTrace();
				System.exit(1);
			}
		}
		
		//多路复用器关闭后，所有注册在上面的Channel和Pipe等资源都会被自动去注册并关闭，所以不需要重复释放资源
		if(selector != null){
			try{
				selector.close();
			}catch(IOException e){
				e.printStackTrace();
			}
		}
	}
	
	private void handleInput(SelectionKey key) throws IOException{
		if(key.isValid()){
			//判断是否连接成功
			SocketChannel sc = (SocketChannel)key.channel();
			if(key.isConnectable()){//接收connect事件进行处理
				if(sc.finishConnect()){//判断连接结果，如果连接成功，注册读事件到多路复用器
					sc.register(selector, SelectionKey.OP_READ);//注册读事件到多路复用器
					doWrite(sc);
				}else{
					System.exit(1);//连接失败，进程退出
				}
			}
			if(key.isReadable()){//接收读事件进行处理
				ByteBuffer readBuffer = ByteBuffer.allocate(1024);
				int readBytes = sc.read(readBuffer);//异步读客户端请求消息到缓冲区
				if(readBytes > 0){
					readBuffer.flip();
					byte[] bytes = new byte[readBuffer.remaining()];
					readBuffer.get(bytes);
					String body = new String(bytes, "UTF-8");
					System.out.println("Now is : " + body);
					this.stop = true;
				}else if(readBytes < 0){
					//对端链路关闭
					key.cancel();
					sc.close();
				}else{
					;//读到0字节，忽略
				}
			}
			
		}
	}
	
	private void doConnect() throws IOException{
		//如果直接连接成功，则注册到多路复用器上，发送请求消息，读应答
		if(socketChannel.connect(new InetSocketAddress(host, port))){//判断是否连接成功，如果连接成功，则直接注册读状态位到多路复用器中
			socketChannel.register(selector, SelectionKey.OP_READ);
			doWrite(socketChannel);
		}else{//如果当前没有连接成功（异步连接，返回false，说明客户端已经发送了sync包，服务端没有返回ack包，物理链路还没有建立）
			socketChannel.register(selector, SelectionKey.OP_CONNECT);//向Reactor线程的多路复用器注册OP_CONNECT状态位，监听服务端的TCP ACK应答
		}
	}
	
	private void doWrite(SocketChannel sc) throws IOException{
		byte[] req = "QUERY TIME ORDER".getBytes();
		ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
		writeBuffer.put(req);
		writeBuffer.flip();
		sc.write(writeBuffer);
		if(!writeBuffer.hasRemaining()){
			System.out.println("Send order 2 server succedd.");
		}
	}
}
